Answer:
.c. Load them via your login script.
Explanation:
Given that using functions in shell scripts enhances programming output and login script comprises the functions and statements required to effectively execute at any given time the user logs into their account.
Hence the moment these functions are formulated, they are then executed through a single command statement thereby reducing the time of re-writing another set of code repeatedly in every program.
Therefore, in this case, what you can do is to "Load them via your login script."
